Chemistry flashcards (C3a)

Pregunta	Respuesta
What is Newlands' Law of Octaves?	every eighth element had similar properties.
Why was Newlands' work criticised?	- the groups contained elements that didn't have similar properties. - metals and non-metals were mixed up. - no gaps were left for undiscovered elements.
How did Mendeleev order the elements?	he ordered the elements in order of atomic mass.
What did Mendeleev do, that Newlands' didn't do?	he left gaps in order to keep elements with similar properties in the same groups.
What do the group 1 elements consist of?	alkali metals.
As you go down the group...	- the elements become more reactive because the the outer electron is more easily lost because it is further from the nucleus. - the elements have lower melting/boiling points.
What type of bond do the alkali metals form?	ionic bonds with non-metals.
Why are the alkali metals keen to lose their outer electron?	to form a +1 ion.
Alkali metals react with water to produce...	hydrogen gas.
Alkali metals form...	hydroxides that dissolve in water that turn a solution alkaline.
What do the group 7 elements consist of?	the halogens.
As you go the group...	- the elements are less reactive because it's harder to gain an electron because the outer energy level is further from the nucleus. - higher melting/boiling points.
What type of bond do the halogens form?	ionic bonds with non-metals.
What ion is formed when the halogens bond with metals?	-1 ion called halides.
What can a more reactive halogen do to a less reactive one?	it can displace a less reactive halogen from an aqueous solution of it salt.
Transition elements are good conductors of...	heat and electricity.
What are the physical properties of transition elements?	dense, strong and very shiny.
Compared to the alkali metals, the transition elements are...	less reactive (don't react as well with water and oxygen).
Compared to the alkali metals, the transition elements are also...	denser , stronger, harder and have higher melting points.
How many ions does a transition element often have?	typically more than one.
With soft water, you get...	a lather.
With hard water, you get...	nasty scum.
What makes water 'hard'?	dissolved calcium and magnesium ions.
What happens when hard water is heated?	it forms calcium carbonate, which 'furs' up appliances.
What are calcium ions good for?	teeth and bones.
What causes temporary hard water?	hydrogencarbonate ion in calcium hydrogen carbonate.
What cause permanent hard water?	dissolved calcium sulphate.
How is temporary hardness removed?	boiling the water.
What happens when temporary hard water is boiled?	calcium hydrogencarbonate decomposes to form calcium carbonate (insoluble)
What is an ion exchange column?	the calcium/magnesium ions that are in the water are exchanged for the sodium ions in the resin.

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